This invention relates to a display device using liquid crystal, electroluminescence, or the like, and more particularly to a thin type display device on which a driving circuit for the liquid crystal, the composition exhibiting electroluminescence or the like is mounted.
Recently, display panels using liquid crystal or electroluminescence are being developed and commercialized. These display panels are so thin that they are easily assembled into a thin type appliance. However it is necessary to connect a semiconductor device for driving the display panel to a group of electrodes extending from the end of display panel. The number of these electrodes ranged, depending on the size of display panel, from hundreds to thousands. Such a semiconductor device for driving was assembled in a package such as a flat pack, and mounted on a printed circuit board nearly the same size as that of the display panel. The leads of this package are soldered to the wiring pattern formed on said printed circuit board. This wiring pattern is connected to the electrode disposed on the opposite side of the printed circuit board by way of a through-hole provided in the printed circuit board. The electrodes of the printed circuit board and those of the display panel are formed at equal intervals. Furthermore, the electrodes of the printed circuit board and those of the display panel are connected by elastic connectors alternately laminating conductive regions and insulating regions.
In such a method of construction, the package of the semiconductor device must increase in size as the number of leads is increased, making it hard to mount on the printed circuit board, and as a result, the entire display panel must be made larger. In addition, the electrodes of the printed circuit board must be formed one by one corresponding to those of the display panel. Actually, since electrodes must be formed at pitches of hundreds of micrometers (.mu.m) on a side of tens of centimeters, and the electrode interval on the printed circuit board is subject to cumulative errors due to thermal expansion and other factors, a perfect connection could not be obtained, which led to connection troubles. Furthermore, there were many points of connection. For example, there were at least four points of connection, that is, wire bonding in the package of the semiconductor device, soldering of the package, and two connections of elastic connectors, which was a major cause in lowering the reliability.
In such a conventional construction, the structure of the display panel was extremely large, or the number of connections was too many, which causes a lower reliability of the connection. This occurs because there were too many constituent parts in the structure, and the true structure of the display panel could not be realized.